Wireless communications systems and methods are widely used to communicate wirelessly with users of radioterminals. As is well known to those having skill in the art, wireless communication systems and methods include conventional terrestrial cellular communication systems and methods, satellite communication systems and methods, ancillary terrestrial communication systems and methods that use one or more satellite communication frequencies terrestrially, and combinations of these and/or other systems and methods.
It is becoming increasingly common for radioterminals to be configured to determine their geographic location. One widely used location determination system and method is the Global Positioning System (GPS). As is well known to those having skill in the art, GPS is a satellite navigation system that is funded and controlled by the U.S. Department of Defense, that provides specially coded satellite signals that can be processed in a GPS receiver, enabling the receiver to compute position, velocity and/or time. As used herein, the term “GPS” also includes other systems that can be used to measure locations on the earth, such as GLONASS. Some cellular communication systems are also configured to assist a radioterminal in determining its geographic location.
Cellular communications systems, satellite communications systems, and ancillary terrestrial communications systems may utilize multiple antenna patterns (beams or cells) each of which can serve a substantially distinct geographical area in an overall service region. Because radioterminals typically are mobile and move through many different service areas of a communication system, a centralized database may be used to track the location of radioterminals within the service region. Upon registering with a system, an initial service area of a radioterminal is entered into the database. As the radioterminal moves from area to area, the database is updated to reflect the radioterminal's present location. The database can then be queried to determine which cell and associated base station transceiver and/or satellite beam within the communication system needs to be used to contact the radioterminal.
As used herein, the term “radioterminal” includes cellular communications radiotelephones, satellite communications radiotelephones, and/or ancillary terrestrial communications radiotelephones with or without a multi-line display; Personal Communications System (PCS) terminals that may combine a radiotelephone with data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and/or a pager, Internet/Intranet access, Web browser, organizer, calendar and/or a Global Positioning System (GPS) receiver; and/or conventional laptop and/or palmtop computers or other devices, which include a radio frequency transceiver. A radioterminal also may be referred to herein as a “radiotelephone”, a “wireless terminal” or simply as a “terminal”. As used herein, the term(s) “radiotelephone”, “radioterminal”, “wireless terminal” and/or “terminal” also include(s) any other radiating user device/equipment/source that can have time-varying geographic coordinates by, for example, being portable, transportable, and/or installed in a vehicle (e.g., aeronautical, maritime, or land-based).